The burn-in test referred to above is a test which is carried out with the view of performing an accelerated. extraction of a potential defective condition such as poor recovery properties or short lifetime dwelt in a device to be tested such as LSI or the like actually driven at elevated temperatures, and this test is usually applied to every LSI.
In carrying out this burn-in test, it is necessary to supply an electric source and signal to each terminal of the device, and at the same time, also necessary to withdraw the signal given by the device as tested through each terminal of said device, and there is used a jig for a burn-in test in order to meet the immediate necessities mentioned above.
As the jigs for use in the burn-in test of this sort, there have heretofore been known those as shown in FIGS. 10 and 11.
That is, the above-mentioned figures are to show a jig for burn-in test which is used in carrying out the burn-in test on a device 1 to be tested, such as LSI, for example, QFP or the like. This jig is composed of a base substrate 2 in the form of a rectangular flat plate and a plurality of sockets 3 arranged on the base substrate 2, said base substrate 2 being reinforced mechanically by means of a reinforcing frame 4 arranged on the periphery of the underside thereof.
When the burn-in test is carried out on the device 1 such as LSI or the like, the aforesaid sockets 3 are each designed to fixidly receive said device 1 therein, while positioning said device 1 in each socket 3. On that account, each socket 3 is provided with a receiving compartment equipped with a cover 6 for putting the device 1 in and removing it, said cover 6 opens and closes freely by means of a hinge 5, and a hook 7 which closes said cover 6 while pressing it downward.
Then in the position corresponding to each terminal (outer lead) 1a of the aforesaid device 1, there are arranged metallic springs 8, the top portion of which has been bent in a circular arc form so as to impart spring properties thereto, said metallic springs 8 being fixed by soldering to the base substrate 2 in such a state where the leg portion of each metallic spring 8 penetrates through the interior of said base substrate 2, and a circuit pattern (not shown) connected electrically to each metallic spring 8 extends, passing through said base substrate 2, to an outer terminal 2a provided on the side end of said substrate 2.
Thus, it is designed such that when the device 1 is received in the socket 3 and the cover 6 is closed by means of the hook 7, each terminal 1a of the device 1 is individually connected electrically to each metallic spring 8, and an electric source or signal is supplied to each terminal 1a of the device 1 through each outer terminal 2a extending from each metallic spring 8 and, at the same time, the signals may be taken out individually through each external terminal 2a from said device 1.
Recently, with increasing demand for LSI of high function and high capacity, the terminals of LSI are also highly tensioned and increased in number, for example, QFP having a terminal pitch of 0.3 mm or less and the number of terminals exceeding 200 has now come to be put to practical use.
In the prior example as mentioned above, however, when metallic springs are arranged in the interior of the socket so as to correspond to the narrow-pitched multiple terminals of LSI, it becomes considerably difficult to carry out this processing and, even if metallic springs could be arranged corresponding to said narrow-pitched multiple terminal of LSI, a mold for forming the socket becomes precise and intricate in its structure, thereby increasing the price of the socket and imposing a heavy burden on the testing cost. Moreover, because the surface area of the base substrate to be occupied by the sockets becomes considerably broadened, the number of the sockets that can be loaded on a piece of the base substrate is limited. Thus the prior art example mentioned above involved such a problem that no efficient burn-in test can be performed.